Influence of Ag as alloy additive on the oxygen evolution reaction on Pb/PbO2 electrode

When a Pb/PbO2 electrode is polarised in the PbO2 potential region (phi gre ater than or equal to 1.0 V vs. Hg/Hg2SO4 reference electrode), oxygen is e volved in parallel to PbO2 formation. The rate of oxygen evolution depends on potential, temperature and alloying additives. In this investigation, th e influence of Ag as alloying additive on the oxygen evolution reaction is studied using linear sweep voltammetry. Based on Tafel and Arrhenius plots, the influence of Ag on the oxygen overvoltage and on the activation energy of the process is determined. It was found that Ag from the metal surface is oxidized and Ag ions are incorporated into the PbO2 layer where they dec rease both the activation energy and the oxygen overvoltage of the process. Ag also changes the alpha/beta-PbO2 ratio and the structure of the PbO2 la yer. (C) 2000 Elsevier Science S.A. All rights reserved.